(1) Field of the Invention
This invention relates to a lock for security screen doors and is suitable for other doors or windows which are hingedly mounted.
(2) Description of the Prior Art
Over the years many different types of locks have been proposed and adopted. One common type is the so-called "mortise" lock which is suitable for hinged doors or windows.
To provide added security, deadlocking arrangements have been incorporated into these locks in an attempt to prevent the locks being picked or forced. While these deadlocking arrangements have been successful in certain areas, a problem has been found that these deadlocking arrangements can be circumvented by shaking the door or window to cause the lock tongue to be freed.